How to install Blender on OS X (Blender directories?)
You don't need to install any directories. If you're looking for where the scripts, config and cache folders are, they're in the Application Support folder under your user account directory.


  
  /Users/$USER/Library/Application
  Support/Blender/2.74/cache
  /Users/$USER/Library/Application
  Support/Blender/2.74/config
  /Users/$USER/Library/Application
  Support/Blender/2.74/scripts
  


The cache folder is where the BVH cache files are saved, and you can sometimes free up quite a lot of space by deleting them.

The config folder is where your startup and userpref files are kept.

The scripts/addons folder is where all your installed addons will be. 

There will be separate folder for each version of Blender under Application Support/Blender.

If you're looking for Scripts/Addons/Presets/Modules that come with the Blender install, you have to look inside the Blender.app file. On a Mac, the application appears as a single file, but it's actually a folder with files within it.

If you right click on the Blender.app file, and choose Show Package Contents, you'll see a Contents folder. Open that and you'll see a number of files and folders. The scripts and presets are in the Resources folder.

The file hierarchy is like this:

Blender 2.74.app
+--Contents
   +--Resources
      +--2.74
         +--datafiles
         +--python
         +--scripts